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Introduction

This guide is intended for primary care providers who care for individuals and populations who may be at risk for infection with Mycobacterium tuberculosis. Latent tuberculosis infection (LTBI) is the presence of Mycobacterium tuberculosis in the body without signs and symptoms, or radiographic or bacteriologic evidence of tuberculosis (TB) disease.

Approximately one-third of the world’s population is infected with M. tuberculosis. It is estimated that more than 11 million people in the United States have LTBI, which is about 4% of the total population. While not everyone with LTBI will develop TB disease, about 5 – 10% of infected people will develop TB disease if not treated. This equates to approximately 550,000 to 1,100,000 people who will develop TB at some point in their life, unless they receive adequate treatment for LTBI. Identifying and treating those at highest risk for TB disease will help move toward elimination of the disease. Primary care providers play a key role in achieving the goal of TB elimination because of their access to high-risk populations.

Guidelines for testing and treating LTBI were released by the Centers for Disease Control and Prevention (CDC) and the American Thoracic Society (ATS). They can be found in the June 9, 2000 issue of Morbidity and Mortality Weekly Report (MMWR), entitled Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection.